Embodiments of the present invention relate to a method of fabricating process chamber components.
A substrate processing chamber may be used to process a substrate in an energized process gas, such as a plasma, to manufacture electronic circuits, such as integrated circuit chips and displays. Typically, the process chamber comprises an enclosure wall that encloses a process zone into which a process gas is introduced, a gas energizer to energize the process gas, and an exhaust system to exhaust and control the pressure of the process gas in the chamber. The process chamber may, for example, be used to deposit material on a substrate or to etch material from a substrate. For example, the chamber may be used to sputter deposit a material onto the substrate, such as a metal for example, aluminum, copper or tantalum; or a metal compound such as tantalum nitride or titanium nitride.
The chamber components that are exposed in the chamber, such as the surfaces of a chamber sidewall, ceiling, liner, or deposition ring, are often coated with a coating layer that, for example, may serve to enhance the adhesion of sputtered material onto the coating, to increase the erosion resistant of the underlying material to the plasma in the chamber, or to provide some other desirable property, such as have an electrically conducting surface. For example, a chamber component may be made from aluminum oxide or quartz and plasma spray coated with a coating of aluminum.
In one process for fabricating such components, a ceramic form of a component is prepared by grit blasting the component using a high-energy grit blasting step, and then dipping the component in a concentrated acid solution, such as an HF solution having a concentration of greater than 20%. The grit blasting step may be used to remove an existing coating on the component in a refurbishment process or to prepare the component surface to receive a new coating. The grit blasting steps are performed to achieve a high surface roughness average (Ra) values of greater than 200 micro inch on the component surface. It is believed that the higher roughness values provide better adhesion of the overlying coating on the ceramic form. Thereafter, the component is re-coated, in the case of a refurbishment process, or freshly coated with coating layer, in the case of a new component.
However, such conventional component fabrication methods still often result in components having an unacceptably low component part life, requiring the components to be frequently replaced or re-furbished. For example, when such chamber components are used in PVD processes to sputter deposit material onto a substrate from a target, the sputtered material also accumulates on the surfaces of the component. The accumulated deposits can cause thermal expansion stresses that result in delamination, cracking, and flaking-off of the underlying coating from the ceramic form. The plasma in the chamber can penetrate through the coating cracks or other damaged areas and erode the exposed surfaces of the chamber component, eventually leading to failure of the component.
Thus, it is desirable to have a process that is capable of fabricating a component having desirable surface properties in a substrate processing environment. It is further desirable to have a component which exhibits a good lifetime in fabrication processes in which excessive amounts of sputtered material may deposit on the component. It is also desirable to allow the component, when deteriorated in operation, to be refurbished as needed.
A method of fabricating a component for a process chamber, the component comprising a ceramic form having grains and grain boundary regions, and the method comprising:
(a) bead blasting the component to provide a surface having a roughness average of less than about 150 microinches;
(b) dipping the component into an solution having a concentration of acid or base that is sufficiently low to reduce etching of grain boundary regions of the ceramic form; and
(c) forming a metal coating over at least a portion of the ceramic form.
A method of fabricating a component for a process chamber, the component comprising a ceramic form having aluminum oxide grains and grain boundary regions, and the method comprising:
(a) bead blasting the component to provide a surface roughness having a roughness average of less than about 150 microinches;
(b) dipping the component into a solution comprising one or more of HF, HCl, and HNO3, in a concentration of less than about 10 volume percent; and
(c) forming an aluminum coating over at least a portion of the component by a twin-wire thermal spraying process.
A method of forming a component for a process chamber, the component comprising a ceramic form having aluminum oxide grains and grain boundary regions, and the method comprising:
(a) bead blasting the component to provide a surface roughness having a roughness average of less than about 150 microinches;
(b) dipping the component into a solution comprising less than about 20 volume percent of one or more of KOH or diethylene glycol monobutyl ether; and
(c) forming an aluminum coating over at least a portion of the ceramic form by a twin wire thermal spraying process.